The present invention relates to processes for the preparation of phospholipid-enriched dairy products as nutraceuticals for the formulation of functional foods.
Phospholipids (PLs) are ubiquitous biological substances, making up the membrane material in most cells in both plants and animals. PLs have been used extensively in pharmaceutical compositions, nutritional compounds, and functional foods. As an example, the importance of phosphatidylserine (PS) as a functional ingredient is supported by the US FDA's qualified health claims in which the usage of phosphatidylserine was related to the reduction of cognitive dysfunction and dementia in the elderly.
PLs can be used as a nutraceutical (including a medication, a medical food, a functional food, and a dietary supplement) in various food formulations, drinks, tablets, and bars containing concentrated, nutritional, and/or dietary ingredients. The addition of PLs to dairy formulations is exacerbated by undesirable attributes of a finished product such as unpleasant taste, non-homogenous consistency, unattractive appearance, and/or poor fractionation stability, among others.
U.S. Pat. No. 8,231,922 by Burling et al. (hereinafter referred to as Burling '922) recites a bovine-milk-derived, phosphatidylserine source of natural composition having excellent dispersibility and organoleptic as well as physical stability using PS-enriched milk fractions. As disclosed in Burling '922, natural milk is a poor source of PS, with only ˜27 mg PS/liter in whole milk and ˜10 mg PS/liter in skim milk. Buttermilk provides a better source of PS, with cream-churned buttermilk containing ˜130 mg PS/liter, while butter-oil-derived buttermilk contains ˜250 mg PS/liter. In a society concerned with reducing dietary fat intake, the loss of naturally-occurring PS during the skimming process of removing fat from milk leaves the nutritional benefit substantially depleted. The skimming process is thought to deplete the naturally-occurring PLs in the milk.
Burling '922 further discloses test results for a milk-added, buttermilk-derived PS (2.0% PS) being physically-, chemically-, and organoleptically-stable, with no precipitation. Milk-added, soy-derived PS (21% and 62% from Enzymotec, Israel) was found to be physically unstable, with 70% of the PS precipitating and settling after one week. Moreover, the milk-added, soy-derived PS was found to be organoleptically unstable, acquiring an unpleasant off-taste typical for soy that made the milk almost undrinkable. All comparative formulations were standardized to provide 100 mg of PS for a 200 ml serving of a skim-milk based drink.
Salt-free phospholipids as described by B. F. Szuhaj (see p. 157 in Lecithins: Sources, Manufacture & Uses, American Oil Chemists' Society (AOCS) Press, Champaign, Ill., 1989; Lecithins, American Oil Chemists' Society (AOCS) Press, Champaign, Ill., 1985; and “Lecithin Production and Utilization,” J. American Oil Chemists' Society, pp. 306-309, 1983) which can be isolated and concentrated through selective fractionation are well-known in the art. However, such methods are less desirable due to economic considerations given the relatively low yields of industrially-important PLs such as PS and PA. While enzymatically-processed lecithin as described by Burling '922 can provide relatively high yields, the negative impact of the calcium salts on solubility in water-based solutions make such industrial routes unsuitable for practical production of PS- and PA-enriched dairy products.
Burling '922 emphasizes the challenges posed to formulating water-based products (which inherently include all dairy-based formulations) because of the need to activate the enzyme with calcium in such procedures, the PS often ends as a scarcely dispersible Ca salt. Moreover, Burling '922 points out that another problem associated with the head-group exchange procedure is the small residues of phospholipase D enzyme activity, which lead to instability of PS in water-based liquid systems. Furthermore, PL fractions tend to produce a very unpleasant taste (i.e., organoleptically unstable) in water-based systems.
Schmidt et al. (in Lecithins, AOCS Press, Champaign, Ill., pp. 203-211, 1985) describes hydrolyzed lecithins in which selective hydrolysis is accomplished by employing enzymes for fatty-acid cleavage. Szuhaj (in Lecithins: Sources, Manufacture & Uses, AOCS Press, Champaign, Ill., p. 160, 1989) suggests that such a water-hydration method would ameliorate organoleptic problems in salt-free forms of PS; however, such methods were not related to the calcium salts of PS or PA. Moreover, such suggestions would not be readily discernible as applicable to such calcium salts as they are counter to the teachings of Burling '922.
It would be desirable to have processes for the preparation of PL-enriched dairy products as nutraceuticals for the formulation of functional foods, including non-dairy-derived PS and/or PA. Such processes would, inter alia, overcome the limitations mentioned above.